System and method of applying carbon dioxide during the production of concrete

ABSTRACT

The present disclosure involves systems and methods for applying CO2 to concrete, which may be performed in-situ or through a separate, stand-alone process. According to another embodiment disclosed herein, a system and method for applying CO2 to one or more materials used in the production of concrete is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority from co-pendingU.S. Provisional Patent Application No. 61/760,319, filed Feb. 4, 2013,the entire disclosure of which is hereby incorporated by reference inits entirety.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to systems andmethods used in the production of concrete. More particularly, thepresent disclosure relates to systems and methods for using carbondioxide during the production of concrete.

BACKGROUND OF THE INVENTION

The production of cement and concrete are well known in the art.Concrete has many uses that are highly beneficial in many industries andcan be produced to perform many functions. For example, concrete iswidely used in commercial construction and for municipal projects. Theconcrete used in these projects may be pre-heated, pre-stressed, andreinforced.

Unfortunately, both the production of the cement used in concrete andthe production of concrete are known to produce large amounts of carbondioxide (CO2). According to the US Energy Information Administration,cement manufacturers are a significant source of carbon dioxidepollution in the atmosphere. When cement is produced, the limestonefeedstock is heated and CO2 is released from the limestone. Cementmanufacturers use a significant amount of energy in the cementmanufacturing process to heat the limestone feedstock resulting infurther CO2 releases and hydrocarbon emissions. Systems and methods areknown that have attempted to entrain CO2 in the mixed concrete to reducethe CO2 emissions into the atmosphere. Other systems and methods haveattempted to use CO2 to strengthen the concrete. However, all of theseknown systems and methods have drawbacks or problems associatedtherewith which are addressed in the present disclosure.

SUMMARY OF THE INVENTION

Embodiments of the present invention contemplate novel processes andapparatus directed to the use of carbon dioxide (CO2) in the productionof concrete and/or materials used for producing concrete. Applying CO2to concrete and/or to concrete materials prior to or during productionof the concrete according to the systems and methods of embodiments ofthe present invention has many benefits compared to prior art methods ofproducing concrete.

Among the many benefits of embodiments of the present invention are areduction in the amount of cement needed during concrete production anddecreased energy consumption for the production of concrete. Theaddition of CO2 to concrete in accordance with embodiments of thepresent invention results in a reduction in the cement component weightper unit of concrete, typically measured in pounds cement per cubic yardof concrete or kilograms cement per cubic meter of concrete. By weightand by volume, cement is typically the most expensive part of the largecomponents of the concrete mix. By treating the concrete with CO2, thetotal cost of a cubic meter or cubic yard of concrete is reduced. Inaddition to reducing the amount of cement required to produce concreteand the corresponding reduction in the cost associated with cement inthe concrete mix, the total cost of production of concrete is reduced byadding CO2 to the concrete, allowing a cubic yard of concrete or cubicmeter of concrete to be produced at a lower total cost.

A further benefit of the addition of CO2 to the concrete mix is anincrease in the ratio of water to cement that may be used to produce theconcrete. Freshly mixed concrete produced using the methods and systemsof the present invention achieves a required slump, a measure of theworkability of freshly mixed concrete, although the ratio of water tocement used to produce the concrete is greater than is possible forconcrete produced using known methods. Thus, the present inventionimproves the consistency and workability of the freshly mixed concrete.

It is one aspect of the present invention to provide systems and methodsof producing concrete with increased break strength and increased breakstrength consistency compared to concrete produced using known methods.The addition of CO2 to concrete according to embodiments of the presentinvention measurably improves the break strength of the concrete, a keyphysical property of concrete, compared to control samples of concreteproduced using known methods. Break strength tests of concrete samplesproduced and treated with CO2 using the methods and apparatus ofembodiments of the present invention show that the variability of breakstrength is reduced between 50% and 80% compared to concrete producedusing other known methods. Further, treating concrete with CO2 resultsin a more consistent concrete mix. Thus, the present invention allowsconcrete producers and users to formulate more precise concrete mixdesigns for the desired structural properties of the concrete treatedwith CO2.

Another benefit of the present invention is a reduction in thetemperature of the fresh mix concrete. When liquid carbon dioxide isinjected from a tank or storage container into a mixer, the liquidcarbon dioxide changes phase to both gaseous and solid carbon dioxide atatmospheric pressure. At atmospheric pressure, the solid CO2 must be−109° F. (−78.5° C.) or less. Consequently, CO2 applied to mixingconcrete according to embodiments of the present invention cools thefresh concrete mix in proportion to the amount of CO2 injected into theconcrete mix. Reducing the temperature of fresh mix concrete is known toincrease the strength of the cured concrete. Methods and apparatus toreduce the temperature of concrete are generally known in the art asdisclosed in U.S. Pat. No. 8,584,864 and U.S. patent application Ser.No. 14/056,139 which are incorporated herein in their entirety byreference. Thus, by cooling the concrete mix, embodiments of the presentinvention increase the strength of the resulting cured concrete.

The systems and methods of embodiments of the present invention alsoproduce concrete with reduced permeability and a reduced degradationrate, thereby increasing the service life of the concrete and structuresmade with the concrete. Those of skill in the art know that thecarbonation level of concrete increases over time, reducing thepermeability of the concrete. In other words, the small interstitialspaces within the concrete are filled in by the carbonation productsfrom the carbonation reaction. The present invention speeds up thecarbonation process resulting in an initial concrete product with lesspermeability compared to concrete produced using known methods. A lesspermeable concrete is less susceptible to environmental degradationwhich occurs when oxygen, water, and other liquids or contaminatespermeate the concrete and cause oxidation (or “rust”) of the steelreinforcing members within the concrete. Normal freeze/thaw cycles canalso reduce the strength of the concrete permeated by oxygen, water, andother liquids by creating fissures within the concrete structure. Thus,structures made with concrete produced by embodiments of the systems andmethods of the present invention have an increased service life.

Embodiments of the present invention also help decrease the CO2footprint of cement and concrete production by trapping and/orsequestering CO2 in the concrete and reacting with CO2 during hydrationof the cement during the concrete mixing process. The amount of energyconsumed during the production of concrete using methods and systems ofthe present invention is also reduced because the amount of cementrequired to produce a given amount of concrete is reduced. By consumingCO2 in the production of concrete, the present invention reducesemissions of CO2, a known greenhouse gas believed to contribute toglobal warming, during the production of concrete. In addition, byreducing the amount of cement needed to produce concrete, embodiments ofthe present invention further reduce energy consumption and greenhousegas emissions of cement manufacturers.

It is another aspect of embodiments of the present invention to providea system and method for applying CO2 in a concrete production process.According to varying embodiments, this application may take the form ofentraining, sequestering or consuming CO2 during the production ofconcrete or concrete material(s) used in the production of concrete. Invarying embodiments described herein, the system and method may beperformed “in-situ” where the materials for producing concrete arestored (such as in large containers or “pigs,” or other storage devicesat the production site) or may alternatively be performed through aseparate sub-process. Embodiments of the present invention trap and/orsequester CO2 in the concrete resulting in reduced CO2 emissions duringthe production of concrete and decreasing greenhouse gas pollution.Applicant's invention includes special controls, injections, and devicesto apply CO2 during the production of concrete, which are described andshown below.

In one embodiment, an apparatus for applying carbon dioxide to concreteor concrete materials is provided. The apparatus includes a storagecontainer for storing liquid carbon dioxide. At least one load cell isaffixed to the storage container for determining a weight of the storagecontainer and the carbon dioxide stored therein. The at least one loadcell is in communication with a system controller and the at least oneload cell is operable to transmit information related to the weight tothe system controller. Piping interconnects the storage container to aninjection assembly. The piping is operable to transport the carbondioxide to the injection assembly. The piping is operable at atemperature and at a pressure required to maintain the carbon dioxide ina liquid state. In one embodiment, the interconnection of the piping tothe storage container is adapted to extract only liquid carbon dioxidefrom the storage container. A control valve is proximate to the storagecontainer and is operable to prevent carbon dioxide from entering thepiping when the control valve is in a closed configuration and thecontrol valve enables carbon dioxide to enter the piping when thecontrol valve is in an open configuration. The control valve is incommunication with the system controller.

The apparatus includes a liquid-gas separator in fluid communicationwith the piping to separate gaseous carbon dioxide from liquid carbondioxide before the injection assembly receives the carbon dioxide. Theliquid-gas separator has a vent to release the gaseous carbon dioxidefrom the apparatus. In one embodiment, the gaseous carbon dioxide isreleased through the vent to the atmosphere. In another embodiment, thegaseous carbon dioxide separated from liquid carbon dioxide by theliquid-gas separator is returned to the storage container by secondpiping interconnecting the storage container to the vent of theliquid-gas separator.

The injection assembly receives carbon dioxide from the piping andinjects carbon dioxide into a concrete mixer or a concrete materialcontainer. In one embodiment, the injection assembly is operable tocause a temperature of carbon dioxide to decrease to no more than about−109° F. when carbon dioxide passes through the injection assembly. Inanother embodiment, the injection assembly injects between about 1 andabout 27 pounds of carbon dioxide into the mixer or concrete materialcontainer for each cubic yard of concrete mix in the mixer or thematerial container. In still another embodiment, the injection assemblyis operable to cause carbon dioxide to change state to a mixture ofsolid carbon dioxide and gaseous carbon dioxide and to inject themixture of solid and gaseous carbon dioxide into the mixer.

The system controller is operable to control the control valve, theinjection assembly, the liquid-gas separator, the mixer, and othersensors and controlled devices in communication with the systemcontroller. In one embodiment, the system controller is operable to senda signal to move the control valve to the closed configuration when thesystem controller determines that the weight of the storage containerand carbon dioxide stored therein has decreased by a predeterminedamount. In another embodiment, the system controller is operable to senda signal to move the control valve to the closed configuration after apredetermined amount of time.

In one embodiment, the apparatus further comprises a mass flowcontroller in fluid communication with the piping and in communicationwith the system controller. The mass flow controller measures a mass ofcarbon dioxide that flows through the mass flow controller and transmitsinformation related to the mass to the system controller. The systemcontroller is operable to send a signal to move the control valve to theclosed configuration when the system controller determines that apredetermined mass of carbon dioxide has flowed through the mass flowcontroller. In still another embodiment, the apparatus further includesa liquid carbon dioxide sensor operable to determine when gaseous carbondioxide is in contact with the control valve of the piping. The liquidcarbon dioxide sensor is in communication with the system controller andoperable to transmit information related to the contact to the systemcontroller. The system controller is operable to send a signal to movethe control valve to the closed configuration when the liquid carbondioxide sensor determines that gaseous carbon dioxide is in contact withthe control valve. In yet another embodiment of the present invention,the apparatus is controlled by the system controller.

In one embodiment, the apparatus further comprises the materialcontainer. The material container includes a plurality of injectors withoutlets facing an interior chamber of the material container. Theplurality of injectors include inlets on an exterior surface of thematerial container. The inlets of the plurality of injectors areinterconnected to the injection assembly. In still another embodiment,the material container includes a closure to seal the interior chamberand the interior chamber can be pressurized after it is sealed. Thesystem controller is operable to control the inlets of the plurality ofinjectors and can send signals to open and close one or more pressurevalves interconnected to the material container to increase or decreasethe pressure within the interior chamber. The system controller isfurther operable to control each of the inlets of the plurality ofinjectors individually and to control the one or more pressure valvesindividually. Thus, the system controller can send a signal to decreasea flow of carbon dioxide to one inlet or to a plurality of inlets, andcan send a second signal to a second inlet or to a plurality of inletsto increase a flow of carbon dioxide through the second inlet orplurality of inlets.

In another embodiment the apparatus includes the mixer. The mixer has amixing chamber with an aperture. The mixing chamber receives carbondioxide from the injection assembly and the predetermined amount ofconcrete materials. The mixing chamber is operable to mix carbon dioxideand the predetermined amount of concrete materials. In yet anotherembodiment, a closure is interconnected to the mixer to seal theaperture of the mixing chamber and the mixing chamber is pressurizedafter the closure seals the aperture. The mixing chamber is operable tomix carbon dioxide and the predetermined amount of concrete materials inthe pressurized mixing chamber. In still another embodiment, thecontroller is operable to send signals to start and stop the mixer, toopen and close the closure, to send signals to open and close one ormore pressure release valves interconnected to the mixing chamber of themixer.

It is another aspect of embodiments of the present invention to providea method of applying carbon dioxide to concrete during the production ofthe concrete, the method generally comprising: (1) determining if thereis sufficient carbon dioxide in a storage container; (2) afterdetermining there is sufficient carbon dioxide in the storage container,starting a mixer; (3) placing a predetermined amount of concretematerials in a mixing chamber of the mixer, wherein the mixing chamberhas an aperture; (4) determining if an injection assembly is in aposition to inject carbon dioxide into the mixing chamber of the mixer,wherein the injection assembly is in fluid communication with thestorage container by piping interconnected to the storage container, acontrol valve, a liquid-gas separator, and the injection assembly; (5)after determining the injection assembly is in the position to injectcarbon dioxide into the mixing chamber, moving the control valve to anopen configuration to allow liquid carbon dioxide to leave the storagecontainer and enter the piping; (6) separating gaseous carbon dioxidefrom liquid carbon dioxide in the piping by the liquid-gas separator,wherein gaseous carbon dioxide is released from the piping through avent to the atmosphere, and wherein liquid carbon dioxide continuesthrough the piping to the injection assembly; (7) injecting carbondioxide into the mixing chamber of the mixer by the injection assembly,wherein the injection assembly is operable to cause liquid carbondioxide to change state to a mixture of solid carbon dioxide and gaseouscarbon dioxide; (8) determining that a predetermined amount of carbondioxide has been injected into the mixing chamber of the mixer; (9)after determining that the predetermined amount of carbon dioxide hasbeen injected into the mixing chamber, moving the control valve to aclosed configuration to prevent the liquid carbon dioxide from leavingthe storage container; (10) mixing the concrete materials and carbondioxide until a chemical reaction between the concrete materials andcarbon dioxide is complete; and (11) discharging the concrete from themixing chamber of the mixer. In one embodiment, the method is controlledby a system controller.

Optionally, the method may further comprise sealing the aperture of themixing chamber with a closure after placing the concrete materials andcarbon dioxide in the mixing chamber, and increasing the pressure in themixing chamber after sealing the aperture of the mixing chamber. In oneembodiment, the method includes adding at least one of a water reducerand an air entrainment agent to the concrete materials in the mixingchamber of the mixer. In one embodiment, the water reducer is BASFPozzolith® 200 N. In another embodiment, the water reducer is BASFPozzolith® 322. In yet another embodiment, the water reducer is BASFGlenium® 3400 NV. In one embodiment, the air entrainment agent is BASF'sMB-AE™ 90. It shall be understood that other water reducers, airentrainment agents, and admixtures may be used with the method andapparatus of the current invention and are within the scope and spiritof the present invention as will be recognized by one of ordinary skillin the art.

In still another embodiment, determining that the predetermined amountof carbon dioxide has been injected into the mixing chamber of the mixercomprises as least one of measuring a weight of the storage containerand/or measuring a mass of carbon dioxide that has flowed from thestorage container.

In another aspect of the present invention, a method of applying carbondioxide to concrete materials used in the production of the concrete isprovided. The method generally comprises: (1) providing a supply ofcarbon dioxide in a storage container; (2) placing concrete materials ina chamber of a material container, wherein the material container has aplurality of injectors, wherein each of the plurality of injectors has avalve to control the flow of carbon dioxide through the injector,wherein each of the plurality of injectors has an inlet on an exteriorsurface of the chamber, and wherein each of the plurality of injectorshas an outlet directed into the chamber; (3) interconnecting the storagecontainer to the inlets of the plurality of injectors of the materialcontainer; (4) moving a control valve in fluid communication with thestorage container and the plurality of injectors to an openconfiguration to allow the carbon dioxide to leave the storage containerand pass through the plurality of injectors into the chamber of thematerial container; and (5) moving the control valve to a closedconfiguration after determining that a sufficient amount of carbondioxide has been added to the concrete materials in the materialcontainer. In one embodiment, a water reducer and/or an air entrainmentagent may be added to the concrete materials in the mixer. In anotherembodiment, the water reducer is BASF Pozzolith® 322. In yet anotherembodiment, the water reducer is BASF Glenium® 3400 NV. In oneembodiment, the air entrainment agent is BASF's MB-AE™ 90. It shall beunderstood that other water reducers, air entrainment agents, andadmixtures may be used with the method and apparatus of the currentinvention and are within the scope and spirit of the present inventionas will be recognized by one of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart diagram of a system for applying CO2 in a concreteproduction process according to a preferred embodiment of the presentinvention;

FIG. 2 is a system for applying CO2 to concrete materials according toanother embodiment of the present invention;

FIG. 3 is a system for applying CO2 in a concrete production processaccording to yet another embodiment of the present invention;

FIG. 4 is flowchart diagram of a preferred embodiment of a method forapplying CO2 according to the present invention and which relates to thesystem depicted in FIG. 3; and

FIG. 5 is a block diagram of a system controller according to anembodiment of the present invention.

To assist in the understanding of embodiments of the present invention,the following list of components and associated numbering found in thedrawings is provided below:

Number Component 2 System 4 Storage container 6 Piping 8 Mixer 10 Tankisolation valve 12 Liquid/gas sensing instrument 14 Automated injectionvalve 16 Injection assembly 17 Injector 18 System 20 Shut-off valve 22Pressure reducing valves 24 Gas purifier 26 Pumping connection 28 Flange30 Valve 32 Mass flow controller 33 Material container 34 System 36Carbon dioxide 38 Load cells 40 Connection 42 System controller 44Concrete materials 46 Position sensors 48 User interface 50 Electronicdevice 52 Wired network 54 Wireless network 56 Control valve 58Liquid-gas separator 59 Liquid CO2 sensor 60 Gaseous carbon dioxide 62Inlet 64 Outlet 66 Solid carbon dioxide 68 Concrete 70 Method 72 Start74 Adjust set point of desired amount of CO2 76 Determine amount of CO2in storage container 78 Start mixer 80 Mixer filled 82 Determineposition of injector assembly and mixer 84 CO2 delivery initiated 86Control valve opened 88 CO2 leaves storage container 90 Liquid andgaseous CO2 separated 92 Liquid CO2 enters inlet of injection assembly94 Liquid CO2 changes state 96 Solid and gaseous CO2 discharged fromoutlet into mixer 98 Determine amount of CO2 delivered 100 Control valveclosed 102 Determine if concrete mixed and CO2 reaction complete 104Concrete discharged 106 End of method 110 Computer 112 Sensor array 114Controlled devices 116 Memory 118 Processor 120 Controller 122 Display124 Input device

DETAILED DESCRIPTION

Although the following text sets forth a detailed description containingdifferent elements, it should be understood that the legal scope of thedescription is defined by the words of the claims set forth at the endof this disclosure. The detailed description is to be construed asexemplary only and does not describe every possible embodiment sincedescribing every possible embodiment would be impractical, if notimpossible. Numerous alternative embodiments could be implemented, usingeither current technology or technology developed after the filing dateof this patent, which would still fall within the scope of the claims.

According to certain embodiments of the present invention, systems andmethods of applying CO2 to concrete, or alternatively to one or more ofthe concrete materials used in the production of concrete, are depictedin FIGS. 1-5. Referring now to FIG. 1, a system 2 for applying CO2 toconcrete, or concrete materials, according to a preferred embodiment isillustrated. A vessel or storage container 4 is utilized to store liquidCO2. The storage container 4 may be of any material, shape, or sizeknown to those of skill in the art and may be positioned generallyvertically or horizontally. Piping 6 or other conduit interconnects thestorage container 4 to a mixer 8 and is utilized to transport apredetermined amount of CO2 to the mixer 8. The piping 6 may be flexibleor generally rigid. In one embodiment, at least a portion of the piping6 is comprised of a flexible ultra-high vacuum (UHV) hose. Various typesof mixers 8 known to those of skill in the art may be used with theembodiments of the present invention, including, for example, tilt drummixers, single and twin shaft compulsory mixers, paddle mixers,pressurized reactor/mixers, truck mounted mixers, transit mix truckscontinuous mixers, and mixers with mixing chambers that can be sealedwith a closure.

The system 2 includes one or more of a tank isolation valve 10, aliquid/gas sensing instrument 12, and an automated injection valve 14 toregulate the flow of CO2 between the storage container 4 and the mixer8. One or more injection assemblies 16, which may also be referred to assnow horns, apply the CO2 to the concrete and/or directly to one or moreof the concrete materials used in the production of concrete. Snow hornssuitable for use as injection assemblies 16 with the current inventionare generally known. For example, U.S. Pat. No. 3,667,242 entitled“Apparatus for Intermittently Producing Carbon Dioxide Snow by Means ofLiquid Carbon Dioxide,” which is incorporated by reference herein in itsentirety, generally discloses an improved snow horn for producing carbondioxide snow in a controlled intermittent manner upon demand.

The CO2 is generally injected into the mixer 8 while the concretematerials are beginning to combine during mixing. The CO2 may be appliedto the concrete or the concrete materials in a gaseous, liquid, or solidstate. The injection assemblies 16 permit dispensing the CO2 directlyinto mixers 8 of all types.

The injection assemblies 16 may be situated to communicate CO2 to theconcrete mixer 8 in use during production at a concrete productionfacility, central mix batch plant, or at a job site. Alternatively, theconcrete mixer 8 may be replaced by a material container or otherstructure (including a stack or pile of concrete materials) housing theconcrete or concrete materials used in producing concrete. For example,carbon dioxide may be delivered by the system 2 to concrete materialsstored at a jobsite using existing structures and equipment. At thejobsite, cement and other concrete materials normally rest in a materialcontainer, such as, in the case of cement, a container known as a “pig.”The interior surface of the material containers include a plurality ofinwardly facing injector outlets. Tubing or piping interconnects theinlets of the plurality of injectors to a source of compressed air. Inknown equipment, compressed air is injected into the material containerthrough one or more of the plurality of injectors into the concretematerials to “fluidize” the concrete materials such that they flow outof the material container. In addition, compressed air is also ofteninjected into cement in delivery trucks to transfer the cement from thetrucks into the storage facilities. In a preferred embodiment, thesystems and methods of the current invention utilize existing structuresand injectors for fluidizing the concrete materials and cement to applyCO2 to the concrete and/or concrete materials and to achieve thebenefits of applying CO2 described herein. For example, in one preferredembodiment, system 2 is interconnected to injectors of a materialcontainer in place of the source of compressed air. When the concretematerial in the material container is required for the production of abatch of concrete, the system 2 injects compressed gaseous CO2 fromcontainer 4 into the material container through the plurality ofinjectors, fluidizing the concrete material and treating the concretematerial with CO2. Each of the plurality of injectors may beindividually controlled such that the flow of CO2 may be preciselycontrolled and the CO2 can be selectively injected through some or allof the plurality of injectors. Further, the rate of the flow of CO2through each of the plurality of injectors can be individuallycontrolled such that some injectors may be partially opened allowing alow rate of flow of CO2, while other injectors may allow a greater rateof flow of CO2. In alternate embodiments of the present invention, theapplication of CO2 is performed by separate and/or additional equipment,as will be understood from a review of the detailed description anddrawing figures provided herein.

In one embodiment, control of the amount of CO2 applied to the concreteand/or the concrete materials can be accomplished by connecting loadcells (or scales) to the CO2 storage container 4 with constantmonitoring of the weight of the container 4 and the CO2 within thecontainer. A system controller (described below) can be set to open andclose one or more valves when a pre-set weight of the CO2 has beendispensed from the container 4. Said differently, once the controllerdetermines that the combined weight of the storage container 4 and theCO2 therein has decreased by a predetermined amount corresponding to thedesired weight of CO2 to be injected into the concrete mix, the systemcontroller will generate a signal to close one or more valves to stopthe flow of CO2 from the storage container 4, ensuring the proper amountof CO2 has been injected into the concrete and/or concrete materials.The Applicant has found that injecting too much CO2 into the process isundesirable and can negatively impact the quality of the concrete. Thus,monitoring the differential weight of the container 4 to control theamount of CO2 dispensed ensures a predetermined amount of CO2 is appliedto the concrete to achieve the desired design characteristics of theconcrete. The applicant has found that the addition of between about 1to 27 pounds of CO2 per cubic yard of concrete increases the breakstrength and physical properties of the concrete mixture. This is justone example and it should be understood that the amount of CO2 added tothe concrete may vary based upon various design requirements of theconcrete and the components and admixtures added to the concrete. Forexample, in one embodiment, more than about 27 pounds of CO2 is addedper cubic yard of concrete.

Another method of controlling the amount of CO2 applied to the concreteand/or the concrete materials is by a timed application. In thisembodiment, a timer relay switch is set to open a valve 10 and allowinjection of CO2 into the mix for a set amount of time. The length oftime the valve 10 remains open may be determined based on the pressureof the CO2 in the storage container 4 and/or flow rate of the CO2monitored by the injection assembly 16. In yet another embodiment, CO2can be manually added to the concrete and/or concrete materials by auser manually opening and closing one or more valves.

Additional elements and equipment may also be included with the system 2for enhancing the system and method disclosed herein. For example,equipment described in relation to FIGS. 2-5 below may be used with theembodiment of the present invention described above in conjunction withFIG. 1.

Another embodiment of a system 18 for applying CO2 to concrete orconcrete materials is illustrated in FIG. 2. Similar to the system 2discussed above, the system 18 has a storage container 4A containingcarbon dioxide in fluid communication with an injection assembly 16A bypiping 6A, 6B. The piping includes both flexible 6A portions andgenerally rigid 6B portions. The system 18 may include one or more of ashut-off valve 20, pressure reducing valves 22, a gas purifier 24, apumping connection 26 with a flange 28, and one or more valves 30. Theamount of CO2 applied to the concrete mix or the concrete materials iscontrolled by use of a mass flow controller 32 coupled to a cryogeniccontrol valve 30A. The mass flow controller 32 measures and continuouslyreports the mass of CO2 that has flowed through the mass flow controller32 to a system controller (described below). When the system controllerdetermines that a pre-set mass of CO2 has passed through the mass flowcontroller 32, the system controller sends a signal to close the controlvalve 30A, the shut-off valve 20, and/or one or more valves within theinjection assembly 16A. Various mass flow controllers 32 and controlvalves 30A are commercially available and suitable for use withembodiments of the present invention. Two examples of valves that may beused with the present invention include ASCO® cryogenic valves andliquid CO2 solenoid valves. The Sierra® Instruments InnovaMass® 240model cryogenic mass flow controller is one example of a cryogenic massflow controller that is suitable for use in the present invention.Methods of metering the CO2 by weight, time, mass, or manual applicationmay be combined and or used alternatively. In one embodiment, CO2 may beapplied to the concrete mix by a combination of metering CO2 by weightusing load cells, by mass in conjunction with a mass flow controller, bytime, and/or by a manual application. Optionally, the valves 20, 30A andvalves of the injection assembly 16A may be manually opened and closedby a user.

In the embodiment illustrated in FIG. 2, the injection assembly 16A hasbeen interconnected by piping 6A to a plurality of injectors 17 of amaterial container 33, or “pig,” with an interior chamber for storingconcrete materials. The injectors 17 have outlets directed inward orfacing the interior chamber of the material container. Inlets of theinjectors 17 are positioned on an exterior surface of the materialcontainer. Each of the plurality of injectors 17 has a valve that may beactuated to individually control the flow of CO2 through the injector17. The controller is operable to send a signal to each of the pluralityof injectors 17 to open or close the valve of the injector 17 and toincrease or decrease the flow of CO2 through each of the injectors 17.The chamber of the storage container has an aperture that is open. Byopening one or more valves 20, 30, 30A, a supply of carbon dioxide isapplied through the injectors 17 to the interior of the materialcontainer 33, treating the concrete materials in the material container33 with CO2 in accordance one embodiment of the present invention. Inyet another embodiment, liquid CO2 is applied to the concrete materialsin the material container 33. Optionally, a closure may beinterconnected to material container to seal the aperture to prevent theCO2 injected into the material container from escaping. In oneembodiment, the chamber may be pressurized after the aperture is sealedby the closure.

Referring now to FIGS. 3 and 4, a system 34 and a method 70 according toone particular embodiment are illustrated. While a general order of thesteps of the method 70 are shown in FIG. 4, the method 70 can includemore or fewer steps or the order of the steps may be arrangeddifferently than the method 70 illustrated in FIG. 4 and describedherein.

The method 70 starts 72 when a desired amount of carbon dioxide 36 to bedelivered to the mixer 8A is entered 74 into a system controller 42. Theset point can be a weight or mass of CO2. The set point may be selectedfrom a list of predetermined mixtures based on design specifications forthe concrete being produced which may be displayed in a user interface48 in communication with the system controller 42. Alternatively, acustom amount of carbon dioxide to be delivered to the mixer 8A may beentered into the controller 42 by a user through the user interface 48.The user interface 48 may be generated by a portable electronic device50 physically separated from the system controller 42. Examples ofelectronic devices 50 include smartphones, tablet devices, laptopcomputers, other portable computers, or other devices running softwareor an application (or “an app”) adapted to interact with the systemcontroller 42 and capable of communicating with the system controller 42over either a wired 52 or a wireless 54 network. The electronic device50 may generate the user interface 48 to enable a user, such as a cementtruck operator, to access the system controller 42 to control the system34 and method 70. In one embodiment, the user may access, receiveinformation from, and control the system controller 42 and the sensorarray and controlled devices in signal communication therewith by usingan electronic device 50 to communicate with the system controller 42over an internet connection.

After the set point for the desired amount of CO2 to be added to theconcrete mix is entered 74 into the system controller 42, the systemcontroller 42 determines 76 if there is a sufficient amount of carbondioxide in the storage container 4B. Load cells 38 are affixed to thestorage container 4B and constantly monitor the combined weight of thestorage container 4B and liquid carbon dioxide 36 and gaseous carbondioxide 60 contained therein. The combined weight of the storagecontainer 4B and carbon dioxide therein are continuously transmitted bythe connection 40 to the system controller 42. By subtracting the knownempty weight of the container 4B from the combined weight of thecontainer 4B and the carbon dioxide therein, the controller candetermine the weight of CO2 in the storage container 4B. If the systemcontroller 42 determines 76 an insufficient amount of carbon dioxide 36is available, the method 70 returns until a sufficient amount of carbondioxide is available in the storage container 4B. If the systemcontroller 42 determines 76 there is a sufficient amount of carbondioxide available, the method 70 continues to 78 and the systemcontroller 42 sends a signal by connection 40 to start the mixer 8A.

A mixing chamber of the mixer 8A is filled 80 with concrete materials 44(such as, for example rock, sand, other aggregates, water, othercementitious materials, admixtures, and cement) per the desired mixdesign and mixing continues. In one embodiment, sensors in communicationwith the system controller 42 are operable to measure the weight orvolume of the concrete materials 44 to be added to the concrete mix. Thesystem controller 42 is further operable to control conveyors, belts,pipes, or valves required to transport the concrete materials 44 to beadded to the concrete mix to the mixing chamber of the mixer 8A.

Those of skill in the art will recognize that various concrete materials44 and admixtures may be added to the concrete mixer 8A as required bydesign considerations based on the use and desired characteristics ofthe concrete. Concrete materials 44 including, but not limited to,plastic, polymer concrete, dyes, pigments, chemical and/or mineraladmixtures, or similar materials that may be represented in a variety oftypes and composition mixes having various combinations of ingredientsmay be added to the mixer 8A. When combined in the mixer 8A, theselected concrete materials 44 create a concrete with desiredcharacteristics. The Applicant has found that the addition of waterreducers and/or air entrainment agents to the concrete materials 44 inthe mixer 8A is advantageous. Water reducers suitable for use in thepresent invention include, by way of example only, Pozzolith® 200 Nwater-reducing admixture, Pozzolith® 322 N water-reducing admixture, andGlenium® 3400 NV high-range water-reducing admixture, which are eachproduced by BASF. One example of a suitable air entrainment agent isBASF's MB-AE™ 90 air-entraining admixture. It shall be understood thatother water reducers, air entrainment agents, and admixtures may be usedwith the method and apparatus of the current invention and are withinthe scope and spirit of the present invention as will be recognized byone of ordinary skill in the art.

The position of an injection assembly 16B or snow horn relative to themixer 8A is monitored by sensors 46 and transmitted by connection 40 tothe system controller 42. The sensors 46 may comprise optical, linear,or angular position sensors that, among other things, track the relativeand/or absolute positions of the various movable components of theinjection assembly 16B and the mixer 8A and the alignment of stationaryand moveable components. The injection assembly 16B, mixer 8A, andsensors 46 may be moved, positioned, and pointed by the systemcontroller 42. When the system controller 42 determines 82 that theinjection assembly 16B is in an appropriate position relative to themixer 8A, the process 70 continues and the user may initiate 84 thedelivery of carbon dioxide by pressing a “start” button or other buttonon the user interface 48. The system controller 42 then sends a signalby connection 40 to open a control valve 56. The valve 56 opens 86 andliquid 36 carbon dioxide leaves 88 the storage container 4B by deliverypiping 6.

The inventors have found that the efficiency of the system 34 isimproved when substantially all of the CO2 transmitted to the injectionassembly 16B is in a liquid 36 state. The piping 6 and other componentsof the system 34 are designed to operate at temperatures and pressuresrequired to maintain the CO2 in a liquid 36 state once it leaves thestorage container 4B. Additionally, positioning the CO2 storagecontainer 4B as close as possible to the injection assembly 16B reducesthe amount of liquid carbon dioxide 36 that changes phase to a gaseous60 state.

To further increase the ratio of liquid 36 CO2 compared to gaseous 60CO2, the system 34 includes a liquid-gas separator 58 to separate 90 thegaseous carbon dioxide 60 from the liquid carbon dioxide 36. The gaseouscarbon dioxide 60 is returned to the storage container 4B by additionalpiping 6C interconnected to a return valve 56A of the liquid-gasseparator and the storage container. Optionally, the gaseous carbondioxide 60 may be vented into the atmosphere through a release valve orvent. In one embodiment, the liquid-gas separator 58 includes a valve56A with a first position to vent the gaseous carbon dioxide 60 to theatmosphere. The valve 56A has a second position to return the gaseouscarbon dioxide 60 to the storage container 4 b through the additionalpiping 6C. The liquid-gas separator 58 and the valve 56A are in signalcommunication 40 with the system controller 42 and the system controller42 is operable to control the valve 56A.

The percentage of liquid carbon dioxide 36 present in the piping 6 canalso be increased by designing the storage container 4B to retain thegaseous carbon dioxide 60. In one embodiment, the piping 6 isinterconnected to a lower surface of the storage container 4B to extractonly liquid carbon dioxide 36 from the storage container 4 b leaving thegaseous carbon dioxide 60 in the head space of the storage container. Ina preferred embodiment, the piping 6 is interconnected to the bottom ofthe storage container 4B. In addition, the system 34 may include aliquid CO2 sensor 59 adapted to determine if liquid carbon dioxide 36 isin proximity to the control valve 56 and can send information collectedby the sensor 59 to the system controller 42 by connection 40. Theliquid CO2 sensor 59 is further operable to transmit a signal to thesystem controller 42 when gaseous carbon dioxide 60 is in contact withthe piping 6 or the control valve 56. The liquid CO2 sensor 59 can bepositioned proximate to the control valve 56. In one embodiment, aliquid CO2 sensor 59 is positioned inside the storage container 4B.

Optionally, the liquid-gas separator 58 may also include a mass flowcontroller. The combined separation instrument and mass flow controllercontinuously monitors the mass of the gaseous carbon dioxide 60separated and the mass of the liquid carbon dioxide 36 that passesthrough the separation instrument 58 and transmits these masses to thesystem controller 42 by connection 40. The system controller 42 mayoptionally use the information transmitted from the mass flow controllerto determine when the pre-set amount of CO2 has been delivered and thensend a signal to close the control valve 56.

After passing through the separator 58, the liquid carbon dioxide 36continues through the piping 6 and enters 92 an inlet 62 of theinjection assembly 16B. The pressure differential from the inlet 62 ofthe injection assembly 16B to the outlet 64 of the injection assembly16B causes the carbon dioxide to change state 94 from a liquid 36 to agas 60 and from a liquid 36 to a solid 66 so that the CO2 ejected fromthe outlet 64 of the injection assembly 16B is a mixture of solid carbondioxide 66 snow and gaseous carbon dioxide 60. The pressure differentialalso causes the temperature of the CO2 to decrease. In one embodiment,the pressure differential causes the temperature of the CO2 to decreaseto no more than −109° F. In another embodiment, the temperature of theCO2 decreases to less than −109° F. The mixture of solid 66 and gaseous60 carbon dioxide is discharged 96 into the mixer 8A.

According to a preferred embodiment of the present invention, theconcrete 68 is mixed in a CO2 atmosphere created by flooding the mixingchamber of the mixer 8A with CO2. The mixing chamber may have an openaperture. In some embodiments of the present invention, a closureadapted to seal the aperture may be interconnected to the mixer 8A. Themixing chamber of the mixer 8A contains air which has been intentionallyenriched with CO2. According to this embodiment, substantially all theair in the mixing chamber is replaced with gaseous CO2.

It is one aspect of embodiments of the present invention to mix theconcrete 68 and CO2 in a mixer 8A with a mixing chamber that has anaperture that can be sealed with a closure. The mixing chamber is loadedwith concrete materials 44 (such as rock, sand, aggregates, water,cement, and/or materials and admixtures) and CO2 according to apredetermined mix design as described above. Optionally, the CO2 may beadded to the mixing chamber of the mixer 8A in a liquid state 36. Theaperture of the mixing chamber is then sealed by the closure and themixer 8A started. Optionally, in one embodiment, the CO2 may be injectedinto the mixing chamber after the mixing chamber is sealed by theclosure. The sealed mixing chamber of the mixer 8A may also bepressurized. Pressure sensors within the mixing chamber transmit apressure within the sealed mixing chamber to the system controller byconnection 40. The system controller 42 can control the pressure withinthe sealed mixing chamber by adding a predetermined amount of CO2 to themixing chamber. The controller 42 can also open one or more valvesinterconnected to the mixing chamber to reduce the pressure within themixing chamber to keep the pressure at a predetermined amount or to ventthe pressure prior to opening the closure sealing the aperture of themixing chamber. Pressurized reactors that keep materials sealed in amixing chamber during a mixing process are known to those of skill inthe art. Mixing the concrete materials 44 and CO2 in a sealed mixingchamber results in almost all of the CO2 being sequestered in theconcrete 68 during the mixing process, achieving a more completereaction and greater saturation of CO2 in the concrete materials 44.

In another embodiment, solid carbon dioxide 66 may be added to theconcrete materials 44 in a mixer 8 with either an open or sealed mixingchamber. In this embodiment, the solid carbon dioxide 66 will react withand sublimate into the concrete 68 during the mixing of the concretematerials 44. The system may also comprise a slinger/crusher for usewith solid carbon dioxide 66 blocks or dry ice. Regular water ice inblock form may be added to the concrete mix in place of mix water forthe purposes of hydrating and cooling the mix simultaneously.

Equipment known in the industry which is used for grinding up water iceblocks and adding the ground ice into the concrete mix in the mixer 8can be modified to accept solid carbon dioxide 66 blocks for addition tothe concrete mix. Using solid carbon dioxide 66 both treats the concretemix with CO2 and cools the concrete mix.

The system controller 42 continuously monitors the load cells 38 andoptionally the mass information transmitted from the optional mass flowcontroller to determine 98 the amount by weight or mass of carbondioxide 36 that has left the storage container 4B. When the systemcontroller 42 determines 98 that the desired or set amount of carbondioxide 36 has been delivered, the system controller 42 sends a signalby connection 40 to close the control valve 56. The control valve 56closes 100 and the flow of carbon dioxide from the storage container 4Bstops. Optionally, the system controller 42 can control the amount ofCO2 delivered to the mixer 8A by sending a signal to close the controlvalve 56 a predetermined amount of time after the control valve 56 wasopened. The system controller 42 is also operable to control the rate ofCO2 delivered to the mixer 8A by sending a signal to the control valve56 to increase or decrease the flow of CO2 through the control valve 56.

The gaseous 60 and solid 66 CO2 in the mixer 8A mixes 98 and chemicallyreacts with the concrete materials 44 to change the physical propertiesof the concrete. The mixer 8A continues to mix the fresh concrete andCO2 until the system controller 42 determines 102 the concrete isthoroughly mixed and that the chemical reaction of the CO2 is complete.The freshly mixed concrete 68 is discharged 104 from the mixer 8A andthe method 70 ends 106. The system controller 42 can send a signal tothe mixer 8A causing the mixer 8A to discharge the mixed concrete and tostop the mixer. The method 70 may repeat to produce subsequent batchesof concrete 68. The system 34 can be scaled to deliver small or largebatches of concrete treated with CO2. For example, in one embodiment thesystem 34 can produce approximately 1,000 cubic yards of concrete perday. However, this is just one example and those of skill in the artwill understand that they system 34 can be designed to produce a largeror a smaller amount of concrete each day.

It is expressly understood in making the foregoing disclosure of thispreferred embodiment that other steps may be included, or certain stepsomitted in the process, and that the steps do not necessarily have tooccur in this precise order to accomplish the benefits described herein.

In all embodiments of the present invention, liquid 36, gaseous 60,and/or solid 66 CO2 may also be injected or applied directly to concretematerials 44 prior to mixing the concrete materials 44 in the mixer 8.Sand, rock, and other fine or coarse aggregates may be treated byinjecting CO2 into aggregate stockpiles, infusing the aggregates withCO2, storing the aggregates in an enriched CO2 atmosphere (for example asealed chamber or storage tank containing gaseous, liquid, and/or solidCO2), or soaking the aggregates in a CO2-rich medium such as carbonatedwater. Cement may be treated with CO2 by altering the production processof cement to increase the amount of CO2 retained in the final product,by injecting CO2 into a cement storage vessel or “pig,” or by storingcement in an enriched CO2 atmosphere. In one embodiment, the cementproduction process may be altered to reduce the amount of CO2 driven offin the process of making cement or by adding CO2 in the process toenrich the cement.

Other cementitious materials used for concrete production, such as flyash, pozzolan, or ground granulated blast furnace slag (GGBFS), can alsobe treated with CO2 prior to being added to a mixer 8 in a mannersimilar to those discussed above. For example, CO2 may be injected intoor added to the other cementitious materials while they are in storageby storing the cementitious material in an enriched CO2 atmosphere.Alternatively, the production process of the cementitious material maybe altered to increase the amount of CO2 retained in the final product,for example, by adding CO2 in the process to enrich the cementitiousmaterial.

Water used in the production of the concrete may also be used as atransport mechanism to add CO2 to the concrete 68 and/or concretematerials 44. CO2 may be injected into the mix water to measurablyincrease the CO2 content of the water. Carbonated mix water may also beused in the production of concrete 68 according to embodiments of thepresent invention. The water may be naturally occurring carbonated wateror may be processed carbonated water enriched with carbon dioxidedirectly or indirectly. Any method of treating or processing water whichincreases the level of CO2 for mix water may be used with embodiments ofthe present invention. In one embodiment, effluent water from a directhydrocarbon fired heater is used to add CO2 to the concrete mix.

Concrete additives and/or admixtures may also be used to add CO2 to theconcrete materials 44 and/or the concrete mix. For example, concreteadditives or compounds which contain CO2, or act to release CO2 into theconcrete mix or promote reaction of CO2 with the concrete mix may beadded to the concrete and/or concrete materials 44. A predeterminedamount of concrete additives or compounds can be added to the concretemix to add a desired amount of CO2 to the concrete 68 based on designcharacteristics of the concrete 68.

Referring now to FIG. 5, a system controller 42 for use with variousembodiments of the present invention is illustrated. The systemcontroller 42 includes a computer 110. The computer 110 may be a generalpurpose personal computer (including, merely by way of example, personalcomputers and/or laptop computers running various versions of MicrosoftCorp.'s Windows™ and/or Apple Corp.'s Macintosh™ operating systems)and/or a workstation computer running any of a variety ofcommercially-available UNIX™ or UNIX-like operating systems. Thecomputer 110 may also have any of a variety of applications, includingfor example, database client and/or server applications, and web browserapplications. Alternatively, the computer 110 may be any otherelectronic device, such as a thin-client computer, laptop,Internet-enabled mobile telephone or smartphone, and/or tablet computer.

The computer 110 is in signal communication via connections 40 with asensor array 112 and controlled devices 114. The computer 110 mayreceive and process information from components of the sensor array 112and the controlled devices 114. The sensor array 112 includes theliquid/gas sensing instrument 12, mass flow controller 32, load cells38, position sensors 46, liquid CO2 sensor 59, and other sensorsincluding pressure sensors, flow rate sensors, thermometers, moistureindicators, timers, etc. Controlled devices 114 are any devices havingan operation or feature controlled by the computer 110 including themixers 8, tank isolation valve 10, liquid/gas sensing valve 12,automated injection valve 14, the injection assembly 16, injectors 17,system shut-off valves 20, pressure reducing valves 22, gas purifiers24, valves 30, mass flow controllers 32, sensors 46, control valve 56,valve 56A, and the liquid-gas separator 58. Controlled devices alsoinclude conveyors, belts, pipes, or valves that transport the concretematerials to the mixer and load the concrete materials into the mixer.The computer 110 generates signals to actuate or control the controlleddevices 114. The computer 110 generally comprises a software-controlleddevice that includes, in memory 116, a number of modules executable byone or more processors 118. The executable modules include a controller120 to receive and process signals from the sensor array 112 andgenerate and transmit appropriate commands to the controlled device 114.

A user interacts with the control system 42 through any means known tothose skilled in the art, including a display 122 and an input device124 such as a keyboard, mouse, or other pointer, and/or gesturescaptured through gesture capture sensors or surfaces, such as a touchsensitive display on a handheld or portable device 50. The term“computer-readable medium” as used herein refers to any tangible storageand/or transmission medium that participates in providing instructionsto a processor for execution. Such a medium may take many forms,including but not limited to, non-volatile media, volatile media, andtransmission media. Non-volatile media includes, for example, NVRAM, ormagnetic or optical disks. Volatile media includes dynamic memory, suchas main memory. Common forms of computer-readable media include, forexample, a floppy disk, a flexible disk, hard disk, magnetic tape, orany other magnetic medium, magneto-optical medium, a CD-ROM, any otheroptical medium, punch cards, paper tape, any other physical medium withpatterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, a solidstate medium like a memory card, any other memory chip or cartridge, acarrier wave as described hereinafter, or any other medium from which acomputer can read. A digital file attachment to e-mail or otherself-contained information archive or set of archives is considered adistribution medium equivalent to a tangible storage medium. When thecomputer-readable media is configured as a database, it is to beunderstood that the database may be any type of database, such asrelational, hierarchical, object-oriented, and/or the like. Accordingly,the disclosure is considered to include a tangible storage medium ordistribution medium and prior art-recognized equivalents and successormedia, in which the software implementations of the present disclosureare stored.

While various embodiments of the present disclosure have been describedin detail, it is apparent that modifications and alterations of thoseembodiments will occur to those skilled in the art. However, it is to beexpressly understood that such modifications and alterations are withinthe scope and spirit of the present disclosure, as set forth in thefollowing claims.

1. A method of carbonating concrete materials during mixing of thematerials comprising (i) placing a predetermined amount of concretematerials in a mixing chamber of a first mixer, wherein the concretematerials comprise cement and water, and mixing the materials in thechamber; (ii) starting addition of carbon dioxide to the mixing chamberso that carbon dioxide contacts the mixing concrete materials and reactswith the cement to produce carbonated concrete materials, wherein thecarbon dioxide comprises solid carbon dioxide; (iii) monitoring theamount of carbon dioxide added to the mixing chamber; and (iv) stoppingaddition of carbon dioxide into the mixing chamber when a predeterminedamount of carbon dioxide has been introduced.
 2. The method of claim 1wherein the predetermined amount of carbon dioxide is between about 1and about 27 pounds of carbon dioxide into the mixing chamber for eachcubic yard of concrete mix in the mixer.
 3. The method of claim 1wherein the carbon dioxide further comprises gaseous carbon dioxide. 4.The method of claim 3 wherein the carbon dioxide comprising solid andgaseous carbon dioxide is produced by flowing liquid carbon dioxide froma container to the mixing chamber through an injection assembly, whereinthe injection assembly is configured to cause the liquid carbon dioxideto convert to gaseous and solid carbon dioxide upon entering the mixingchamber.
 5. The method of claim 1 wherein the amount of carbon dioxideadded to the mixing chamber is monitored by a method comprising (i)monitoring the weight of a carbon dioxide container that supplies thecarbon dioxide added to the mixing chamber; (ii) monitoring the time ofaddition of the carbon dioxide to the mixing chamber; (iii) monitoringthe mass of carbon dioxide added to the mixing chamber; (iv) manuallymonitoring the carbon dioxide added to the mixing chamber; or anycombination thereof.
 6. The method of claim 5 wherein the monitoring ofsteps (i), (ii), and/or (iii) is performed automatically by a controlsystem.
 7. The method of claim 1 wherein the concrete materials furthercomprise aggregate, admixture, other cementitious material, or anycombination thereof.
 8. The method of claim 7 wherein the othercementitious material comprises fly ash, pozzolan, ground granulatedblast furnace slag, or any combination thereof.
 9. The method of claim 1wherein the predetermined amount of carbon dioxide added to the concretematerials in the mixing chamber is an amount that causes the finalconcrete product, when compared to uncarbonated concrete product of thesame mix design, to have one or more of the following enhancedproperties: (i) increased break strength; (ii) increased break strengthconsistency; (iii) decreased permeability; (iv) decreased degradationrate; (v) decreased amount of cement in the concrete mix; and/or (vi)decreased carbon footprint.
 10. The method of claim 1 wherein the mixeris a tilt drum mixer, a single shaft compulsory mixer, a double shaftcompulsory mixer, a paddle mixer, a pressurized mixer, a truck mountedmixer, a transit mix truck continuous mixer, or a mixer with a mixingchamber that can be sealed with a closure.
 11. The method of claim 1wherein the addition of carbon dioxide to the mixing chamber occurs at aconcrete production facility, a central mix batch plant, a job site, ora combination thereof.
 12. The method of claim 1 wherein the carbondioxide is added to the mixing chamber through an injection assemblyconfigured to move relative to the mixer, and wherein the position ofthe injection assembly relative to the mixer is monitored.
 13. Themethod of claim 12 wherein the addition of carbon dioxide to the mixingchamber is started only after the injection assembly is in anappropriate position relative to the mixer for injection of carbondioxide into the mixer.
 15. The method of claim 12 wherein the positionof the injection assembly relative to the mixer is monitoredautomatically.
 16. The method of claim 1 further comprising addingcarbonated mix water to the mixing chamber.
 17. The method of claim 16further comprising carbonating water to produce the carbonated wateradded to the mix chamber.
 18. The method of claim 1 further comprisingmixing the carbonated materials from the first mixer with additionalconcrete materials in a second mixer.
 19. The method of claim 18 whereinthe additional concrete materials comprise aggregate, admixture,additional cementitious materials, or a combination thereof.
 20. Themethod of claim 19 wherein the aggregate comprises sand, rock, or acombination thereof.
 21. The method of claim 19 wherein the additionalcementitious materials comprise fly ash, pozzolan, ground granulatedblast furnace slag, or a combination thereof.
 22. The method of claim 19wherein the admixture comprises a water reducer, an air entrainmentagent, or a combination thereof.
 23. The method of claim 19 wherein thefirst and second mixers are the same mixer.
 24. The method of claim 4further comprising ensuring that substantially all of the carbon dioxidetransmitted to the injection assembly is in a liquid state.